Phase-scanned radiating array

ABSTRACT

A phase-scanned radiating array employing an end-fed radiating waveguide having radiating apertures spaced along the length of one side of the waveguide. A series interconnected plurality of windings is wound about the waveguide and spaced intermediate successive ones of the radiating apertures. A longitudinal ferrite rod, inserted within the waveguide, has axially spaced interruptions in the ferrite material cross section thereof, the spacing corresponding to that of the radiating apertures of the waveguide.

Unite States Carlise atet [191 Dec. 17, 1974 PHASE-SCANNED RADlA-TINGARRAY Robert L. Carlise, Irvine, Calif.

Rockwell International Corporation, El Segundo, Calif.

lnventor:

Assignee:

3,212,031 10/1965 Reggia et al. 333/31 Primary Examiner-Eli LiebermanAttorney, Agent, or Firm-L. Lee Humphries; H. Fredrick Hamann; Rolf M.Pitts [5 7 ABSTRACT A phase-scanned radiating array employing an end-fedradiating waveguide having radiating apertures spaced [63] gy of Mayalong the length of one side of the waveguide. A series interconnectedplurality of windings is wound about the waveguide and spacedintermediate successive 343/768 gd ig ig ones of the radiatingapertures. A longitudinal ferrite [58] Field 4 2 787 rod, insertedwithin the waveguide, has axially spaced interruptions in the ferritematerial cross section 56] References Cited thereof, the spacingcorresponding to that of the radiating apertures of the waveguide.UNITED STATES PATENTS 3,109,174 10/1963 Plummer 343/854 3 Claims, 4Drawing l' Mb g0 /\l I u I u '2 l5c lZc PZJEHTED w: 1 71914 3.855.597

sum 2 g 3 4 FIG.3

PATEI'HEU 9531 7 1974 Him/M PHASE-SCANNED RADIATING ARRAY Thisapplication is a continuation-in-part of application Ser. No. 250,945filed May 8, 1972 by Robert L. Carlise and entitled Phase-ScannedRadiating Array, now abandoned.

BACKGROUND OF THE INVENTION The field of technology to which the subjectinvention relates is phase-scanned antenna arrays or radiatingphase-shifters.

In the design of microwave phase-shifters, it has been known that avariation in magnetization of a ferrite rod inserted in a waveguide maybe utilized to produce variations in the phase shift of microwave energypropagated through such waveguide. Such magnetization change may beproduced by means of varying the excitation of a winding wound about thewaveguide section. Such described assembly, while functioning as amicrowave phase shifter (and known in the art as a Reggia- Spencer phaseshifter), does not readily lend itself to functioning as a phase-scannedradiating array. In other words, where a longitudinal array of slots areplaced in the waveguide, in an attempt to form a phased array antenna orphase-controlled radiating feedline, it is found that such structure isof limited efficiency, being useful over only a very narrow orrestricted phase range. As increased phase-scanning is sought byincreasing the magnetization of the ferrite rod, consequent approachingsaturation of the rod reduces coupling to and radiation from the arrayof slots.

BRIEF DESCRIPTION OF THE INVENTION By means of the concept of thesubject invention, the above-noted adverse coupling effects are avoided,and an electronically-scanned radiating feedline is obtained which is ofincreased utility over a wider scan angle range without suffering thedegree of attenuation associated with the prior art.

In a preferred embodiment of the invention, there is provided a modifiedReggia-Spencer microwave delay line, comprising a rectangular waveguidesection containing a ferrite rod structure and having a winding axiallywound about the waveguide section. A longitudinal array of mutuallyspaced apertures or radiating slots is included in one face of thewaveguide section, the windings being arranged between successive slotsto avoid blockage thereof. Further modification of the Reggia-Spencerdelay line includes axially spaced interruptions of a combined magneticand dielectric nature in the ferrite material cross section of theferrite rod, the spacing corresponding to that of the apertures of thewaveguide.

By means of such arrangement of axially spaced interruptions, asaturated ferrite section is avoided in the vicinity of the radiatingapertures, whereby improved energy coupling is obtained, particularlyunder condition of large scan angles or increased phase shift (asproduced by increased ferrite magnetization). Accordingly, an object ofthe invention is to provide an improved phase-scanned array.

Another object of the invention is to provide a phasescanned radiatingfeedline of reduced attenuation over a wider phaseshift range.

A further object is to provide a minimum bulk phasescanned feedlinehaving improved coupling performance.

These and other objects of the invention will become apparent from thefollowing description, when taken together with the accompanyingdrawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic arrangement, inpartial vertical central section, of a device embodying the concept ofthe invention;

FIG. 2 is a view in perspective, partially torn away, of the device ofFIG. 1;

FIG. 3 is a view in perspective showing an alternate (switchable)end-fed, phase-scanned line source, in which the concept of theinvention may be advantageously employed; and

FIG. 4 is an antenna array for providing a uniplanarly electronicallyscanned pencil beam, employing the device of FIGS. 1 and 2.

In the figures, like reference characters refer to like parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis illustrated a schematic arrangement, in partial vertical centralsection, of a device embodying the concept of the invention. There isprovided a rectangular waveguide section 10 having a longitudinal arrayof spaced slots or radiating apertures lla-lln in an H wall thereof(more clearly seen in FIG. 2). Although such slots are shown to beregularly spaced, such spacing may be selected to be otherwise for thepurpose of effecting a desired beam shape, as is understood by thoseskilled in the art. Axially wound about waveguide 10 is a winding 12, soarranged as to avoid blocking apertures Ila-lln. In other words, thereis provided a series-interconnected plurality of component windingsl2a-I2n each axially spaced intermediate successive onesof the radiatingapertures Ila-l In. An additional winding (not shown) may be included oneach end of the waveguide to minimize the end-effect associated withlong solenoids and to ensure a uniform magnetic field in the terminalaxial sections of the ferrite rod relative to the central axial sectionsthereof.

A longitudinal structure or rod 13 is inserted within the waveguidesection 10, the rod 13 being comprised of a ferrite material and havingregularly spaced interruptions l4a-l4n in the ferrite materialcross-section, the spacing of the interruptions corresponding to that ofthe apertures. Such interruptions in such ferrite cross-sectional areamay comprise air gaps or be filled with a solid dielectric material, thedielectric constant of such air gap or other dielectric material beingsubstantially different than that of the ferrite material, whereby botha magnetic and dielectric perturbation are commonly provided by suchspatial interruptions. As illustrated in FIG. 1, such interruptions maybe abrupt and total, and employ dielectric spacers l4a-l4n intermediatethe ferrite axial sections l5a-l5n-l-l, the like axial dimension of eachsuch dielectric spacer being preferably 0.03-0.04 free space wavelength.In manufacture, the mutually axially spaced axial ferrite sections orslugs may be potted or encapsulated in a dielectric compound which iscast so as to fit in and be conveniently positionable in the waveguidesection, whereby the ferrite slugs 15a- 15n+l are adequately supported.Alternatively, the ferrite slugs and dielectric spaces may be taped orwrapped as an integral rod assembly, and the rod assembly potted in suchdielectric compound. Although the rod assembly, as illustrated, has beenshown as circular in cross section, obviously other cross section shapesmay be used, such as rectangular for instance.

The spacing regularity of the series H wall slots lla-l 1n may beselected relative to an integer number of waveguide wavelengths (nhg) toprovide a back scan angle -[3 (for the antenna beam), while a maximummagnetization state of the ferrite slugs corresponds to a broadside beamdirection for an antenna beam formed by the combined radiation from theslots in response to end-fed RF excitation of waveguide 10.

In normal operation of the above-described arrangement, the magneticfield within the ferrite slugs tends to be proportional to the currentthrough solenoid winding 12. Now, the velocity of propagation of theend-fed RF excitation introduced into the loaded waveguide isproportional to the magnetic field in the ferrite material and,therefore, tend to be proportional to the solenoid current in winding12. As is well understood in the art of electronically scanningantennas, the angle (relative to the radiating feed line 10) at which abeam pattern is radiated from slotted line 10 is a function of the slotspacing and the RF propagation velocity within the waveguide. By merelychanging the solenoid current (through winding 12), the propagationvelocity and, hence, the associated beam angle may be correspondinglychanged.

For the backscanned mode described above, the initial back-scan angle,-B,,, is reduced by increasing the applied excitation of solenoid 12from zero, a maximum excitation producing a broadside angle (directionnormal or perpendicular to the axial extent of radiating feedline 10).By then reducing the solenoid excitation to zero and applying the RFexcitation to the opposite end of feed 10 (by means of a double-throw RFswitch such as that described in my copending application Serial No.244,815 forwarded Apr. 14, 1972 now US. Pat No. 3,768,041, the antennamay be made to look at an opposite angle, +13 (displaced from theinitial angle, -B,,, by the amount 2,8); then by again increasing thesolenoid excitation, the look angle is back-scanned or reduced tobroadside (or zero). Thus, by such two oppositely end-fed scanningintervals, a full scanning cycle is" completed by which the antenna isscanned over the range $3 Such alternate (switchable) endfed arrangementis shown more particularly in FIG. 3 by means of a four pin diode,double-throw RF switch 20 having switched portsandcoupled to respectiveends of radiating waveguide by guide sections 110a and 110b, and furtherhaving a common port@(which may be selectively coupled to an alternateone of ports and@, as explained more fully in my above noted copendingapplication Ser. NO. 244,815 now US. Pat. No. 3,768,041.

Although the coupling between the radiating slots and the magnetizableferrite rod assembly has been described as periodic magnetic anddielectric structured interruptions corresponding to the spatialperiodicity of the radiating slots and comprising removals of orreductions in the ferrite crosssectional area, the concept or theinvention is not so limited, and such coupling may be comprised ofmetallic probes radially extending from the rod assembly toward theslots and insulated from both the waveguide wall 10 and the ferrite rod.

The device of FIGS. 1 and 2, having a large system aperture dimension inthe scanning plane or longitudinal direction of the single line arrayand having a narrow system aperture direction normal to the scanningplane, provides a (horizontally) scanning fan beam (wide vertical beamwidth and narrow horizontal beam width). A uniplanarly scanning pencilbeam may be obtained by employing a system of coplanar stacked ormutually parallel radiating feeds l5a-15n each end-fed from acorresponding slot of the radiating phase-shifter line source 10 ofFIGS. 1 and 2, as shown more particularly in FIG. 4. By means of sucharrangement, the plane of the ultimate radiating slots of the antenna isat to the plane of the slots of the phase shifter, the scanningdirection or plane being substantially parallel, however, to thelongitudinal direction of the phase shifter line source 10. Because ofthe large aperture dimension in each direction of the array, a pencilbeam slope results, as is understood in the art. Obviously, thealternate end-fed switching arrangement of FIG. 3 may be employed withline 10 of FIG. 4.

Accordingly, there has been described an improved electronically scannedarray comprising an end-fed slotted waveguide and modifiedReggia-Spenccr type phase shifter, which is of minimum bulk, low-costand high performance.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample only and is not to be taken by way of limitation, the spirit andscope of this invention being limited only by the terms of the appendedclaims.

I claim:

1. A phased-scanned radiating array comprising in combination an end-fedradiating rectangular waveguide having radiating apertures spaced alongthe length of a side thereof,

a series interconnected plurality of windings wound about said waveguideand axially spaced intermediate successive areas of said radiatingapertures, and

a longitudinal ferrite rod inserted within said waveguide, said rodhaving regularly spaced magnetic and dielectric interruptions in theferrite material cross-section thereof, the spacing of saidinterruptions corresponding to that of said apertures,

said interruptions in said ferrite material cross section being filledwith a dielectric material having a dielectric constant substantiallydifferent from that of said ferrite.

2. A phased-scanned radiating array comprising in combination an end-fedradiating rectangular waveguide having radiating apertures spaced alongthe length of a side thereof,

a series interconnected plurality of windings wound about said waveguideand axially spaced intermediate successive areas of said radiatingapertures, and

a longitudinal ferrite rod inserted within said waveguide, said rodhaving regularly spaced magnetic and dielectric interruptions in theferrite material cross-section thereof, the spacing of saidinterruptions corresponding to that of said apertures,

said rod being comprised of successive axial sections alternately offerrite and of a dielectric material,

a longitudinal ferrite rod inserted within said waveguide and parallelto said side, said rod having regularly axially spaced interruptions ofa combined magnetic and dielectric nature in the ferrite materialcross-section thereof, the spacing of said interruptions correspondingto that of said apertures,

said rod being comprised of successive axial sections alternately offerrite and of a dielectric material, the dielectric material axialsections being between 0.03-0.04 free space wavelength in length.

1. A phased-scanned radiating array comprising in combination an end-fedradiating rectangular waveguide having radiating apertures spaced alongthe length of a side thereof, a series interconnected plurality ofwindings wound about said waveguide and axially spaced intermediatesuccessive areas of said radiating apertures, and a longitudinal ferriterod inserted within said waveguide, said rod having regularly spacedmagnetic and dielectric interruptions in the ferrite materialcross-section thereof, the spacing of said interruptions correspondingto that of said apertures, said interruptions in said ferrite materialcross-section being filled with a dielectric material having adielectric constant substantially different from that of said ferrite.2. A phased-scanned radiating array comprising in combination an end-fedradiating rectangular waveguide having radiating apertures spaced alongthe length of a side thereof, a series interconnected plurality ofwindings wound about said waveguide and axially spaced intermediatesuccessive areas of said radiating apertures, and a longitudinal ferriterod inserted within said waveguide, said rod having regularly spacedmagnetic and dielectric interruptions in the ferrite materialcross-section thereof, the spacing of said interruptions correspondingto that of said apertures, said rod being comprised of successive axialsections alternately of ferrite and of a dielectric material, thedielectric material being preselectively axially phase spaced relativeto said regularly spaced apertures and having a dielectric constantsubstantially different from that of said ferrite.
 3. A phase-scannedradiating array comprising in combination an end-fed radiatingrectangular waveguide having radiating apertures spaced along the lengthof a side thereof, a series interconnected plurality of windings woundabout said waveguide and acially spaced intermediate successive areas ofsaid radiating apertures, a longitudinal ferrite rod inserted withinsaid waveguide and parallel to said side, said rod having regularlyaxially spaced interruptions of a combined magnetic and dielectricnature in the ferrite material cross-section thereof, the spacing ofsaid interruptions corresponding to that of said apertures, said rodbeing comprised of successive axial sections alternately of ferrite andof a dielectric material, the dielectric material axial sections beingbetween 0.03-0.04 free space wavelength in length.